218 The Commercial Apple Industry 



Cedar-rust (Gymnosporangium juniperirvirginiance} . 



In some regions, particularly in the Virginias, the cedar- 

 rust has become a serious menace. It appears on the apple 

 in bright yellow spots as large as % to % inch in 

 diameter. In the yellow area are small black specks or 

 pustules. The foliage is similarly affected and late in 

 the season blisters or cushions are found on the under- 

 side of the leaves. The cutting down of all cedar trees 

 within a radius of at least a mile is the principal correc- 

 tive measure. 



Bitter-rot (Glomerella rufomaculans) . 



Bitter-rot is very serious in certain commercial apple 

 regions in the South, particularly in the Piedmont district 

 of Virginia and in parts of the Ozarks. The fungus 

 works in the tissue of the apple, causing first small light 

 brown spots just beneath the skin of the apples. These 

 spots may increase rapidly in size, attaining a diameter of 

 an inch or more, and are usually sunken. Occasionally 

 the apple assumes a peppered appearance and with yellow 

 varieties as the Newtown, the margins of the spots may be- 

 come purple or reddish in color. (See Plate XVI.) 



The disease is spread by spores, transmitted by rain 

 drops, insects or birds. It may appear any time between 

 the middle of June and the middle of September, being 

 favored by warm moist seasons. The Yellow Newtown or 

 Albemarle Pippin is very susceptible and Ben Davis, 

 Gano, Grimes and Jonathan more or less so. 



Bordeaux mixture (4-4-50) applied from June 15 to 

 July 1, July 15 to 20 and August 1 to 5 is generally con- 

 sidered the best control program. The disease winters 



